1 /*- 2 * Copyright (c) 1982, 1986, 1990, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)kern_synch.c 8.9 (Berkeley) 5/19/95 35 */ 36 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD$"); 39 40 #include "opt_ktrace.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/condvar.h> 45 #include <sys/kdb.h> 46 #include <sys/kernel.h> 47 #include <sys/ktr.h> 48 #include <sys/lock.h> 49 #include <sys/mutex.h> 50 #include <sys/proc.h> 51 #include <sys/resourcevar.h> 52 #include <sys/sched.h> 53 #include <sys/signalvar.h> 54 #include <sys/sleepqueue.h> 55 #include <sys/smp.h> 56 #include <sys/sx.h> 57 #include <sys/sysctl.h> 58 #include <sys/sysproto.h> 59 #include <sys/vmmeter.h> 60 #ifdef KTRACE 61 #include <sys/uio.h> 62 #include <sys/ktrace.h> 63 #endif 64 65 #include <machine/cpu.h> 66 67 static void synch_setup(void *dummy); 68 SYSINIT(synch_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, synch_setup, NULL) 69 70 int hogticks; 71 int lbolt; 72 73 static struct callout loadav_callout; 74 static struct callout lbolt_callout; 75 76 struct loadavg averunnable = 77 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */ 78 /* 79 * Constants for averages over 1, 5, and 15 minutes 80 * when sampling at 5 second intervals. 81 */ 82 static fixpt_t cexp[3] = { 83 0.9200444146293232 * FSCALE, /* exp(-1/12) */ 84 0.9834714538216174 * FSCALE, /* exp(-1/60) */ 85 0.9944598480048967 * FSCALE, /* exp(-1/180) */ 86 }; 87 88 /* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */ 89 static int fscale __unused = FSCALE; 90 SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); 91 92 static void loadav(void *arg); 93 static void lboltcb(void *arg); 94 95 void 96 sleepinit(void) 97 { 98 99 hogticks = (hz / 10) * 2; /* Default only. */ 100 init_sleepqueues(); 101 } 102 103 /* 104 * General sleep call. Suspends the current process until a wakeup is 105 * performed on the specified identifier. The process will then be made 106 * runnable with the specified priority. Sleeps at most timo/hz seconds 107 * (0 means no timeout). If pri includes PCATCH flag, signals are checked 108 * before and after sleeping, else signals are not checked. Returns 0 if 109 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 110 * signal needs to be delivered, ERESTART is returned if the current system 111 * call should be restarted if possible, and EINTR is returned if the system 112 * call should be interrupted by the signal (return EINTR). 113 * 114 * The mutex argument is exited before the caller is suspended, and 115 * entered before msleep returns. If priority includes the PDROP 116 * flag the mutex is not entered before returning. 117 */ 118 int 119 msleep(ident, mtx, priority, wmesg, timo) 120 void *ident; 121 struct mtx *mtx; 122 int priority, timo; 123 const char *wmesg; 124 { 125 struct thread *td; 126 struct proc *p; 127 int catch, rval, sig, flags; 128 WITNESS_SAVE_DECL(mtx); 129 130 td = curthread; 131 p = td->td_proc; 132 #ifdef KTRACE 133 if (KTRPOINT(td, KTR_CSW)) 134 ktrcsw(1, 0); 135 #endif 136 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, mtx == NULL ? NULL : 137 &mtx->mtx_object, "Sleeping on \"%s\"", wmesg); 138 KASSERT(timo != 0 || mtx_owned(&Giant) || mtx != NULL, 139 ("sleeping without a mutex")); 140 KASSERT(p != NULL, ("msleep1")); 141 KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep")); 142 143 if (cold) { 144 /* 145 * During autoconfiguration, just return; 146 * don't run any other threads or panic below, 147 * in case this is the idle thread and already asleep. 148 * XXX: this used to do "s = splhigh(); splx(safepri); 149 * splx(s);" to give interrupts a chance, but there is 150 * no way to give interrupts a chance now. 151 */ 152 if (mtx != NULL && priority & PDROP) 153 mtx_unlock(mtx); 154 return (0); 155 } 156 catch = priority & PCATCH; 157 rval = 0; 158 159 /* 160 * If we are already on a sleep queue, then remove us from that 161 * sleep queue first. We have to do this to handle recursive 162 * sleeps. 163 */ 164 if (TD_ON_SLEEPQ(td)) 165 sleepq_remove(td, td->td_wchan); 166 167 sleepq_lock(ident); 168 if (catch) { 169 /* 170 * Don't bother sleeping if we are exiting and not the exiting 171 * thread or if our thread is marked as interrupted. 172 */ 173 mtx_lock_spin(&sched_lock); 174 rval = thread_sleep_check(td); 175 mtx_unlock_spin(&sched_lock); 176 if (rval != 0) { 177 sleepq_release(ident); 178 if (mtx != NULL && priority & PDROP) 179 mtx_unlock(mtx); 180 return (rval); 181 } 182 } 183 CTR5(KTR_PROC, "msleep: thread %p (pid %ld, %s) on %s (%p)", 184 (void *)td, (long)p->p_pid, p->p_comm, wmesg, ident); 185 186 DROP_GIANT(); 187 if (mtx != NULL) { 188 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); 189 WITNESS_SAVE(&mtx->mtx_object, mtx); 190 mtx_unlock(mtx); 191 } 192 193 /* 194 * We put ourselves on the sleep queue and start our timeout 195 * before calling thread_suspend_check, as we could stop there, 196 * and a wakeup or a SIGCONT (or both) could occur while we were 197 * stopped without resuming us. Thus, we must be ready for sleep 198 * when cursig() is called. If the wakeup happens while we're 199 * stopped, then td will no longer be on a sleep queue upon 200 * return from cursig(). 201 */ 202 flags = SLEEPQ_MSLEEP; 203 if (catch) 204 flags |= SLEEPQ_INTERRUPTIBLE; 205 sleepq_add(ident, mtx, wmesg, flags); 206 if (timo) 207 sleepq_set_timeout(ident, timo); 208 if (catch) { 209 sig = sleepq_catch_signals(ident); 210 } else 211 sig = 0; 212 213 /* 214 * Adjust this thread's priority. 215 */ 216 mtx_lock_spin(&sched_lock); 217 sched_prio(td, priority & PRIMASK); 218 mtx_unlock_spin(&sched_lock); 219 220 if (timo && catch) 221 rval = sleepq_timedwait_sig(ident, sig != 0); 222 else if (timo) 223 rval = sleepq_timedwait(ident); 224 else if (catch) 225 rval = sleepq_wait_sig(ident); 226 else { 227 sleepq_wait(ident); 228 rval = 0; 229 } 230 if (rval == 0 && catch) 231 rval = sleepq_calc_signal_retval(sig); 232 #ifdef KTRACE 233 if (KTRPOINT(td, KTR_CSW)) 234 ktrcsw(0, 0); 235 #endif 236 PICKUP_GIANT(); 237 if (mtx != NULL && !(priority & PDROP)) { 238 mtx_lock(mtx); 239 WITNESS_RESTORE(&mtx->mtx_object, mtx); 240 } 241 return (rval); 242 } 243 244 int 245 msleep_spin(ident, mtx, wmesg, timo) 246 void *ident; 247 struct mtx *mtx; 248 const char *wmesg; 249 int timo; 250 { 251 struct thread *td; 252 struct proc *p; 253 int rval; 254 WITNESS_SAVE_DECL(mtx); 255 256 td = curthread; 257 p = td->td_proc; 258 KASSERT(mtx != NULL, ("sleeping without a mutex")); 259 KASSERT(p != NULL, ("msleep1")); 260 KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep")); 261 262 if (cold) { 263 /* 264 * During autoconfiguration, just return; 265 * don't run any other threads or panic below, 266 * in case this is the idle thread and already asleep. 267 * XXX: this used to do "s = splhigh(); splx(safepri); 268 * splx(s);" to give interrupts a chance, but there is 269 * no way to give interrupts a chance now. 270 */ 271 return (0); 272 } 273 274 sleepq_lock(ident); 275 CTR5(KTR_PROC, "msleep_spin: thread %p (pid %ld, %s) on %s (%p)", 276 (void *)td, (long)p->p_pid, p->p_comm, wmesg, ident); 277 278 DROP_GIANT(); 279 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); 280 WITNESS_SAVE(&mtx->mtx_object, mtx); 281 mtx_unlock_spin(mtx); 282 283 /* 284 * We put ourselves on the sleep queue and start our timeout. 285 */ 286 sleepq_add(ident, mtx, wmesg, SLEEPQ_MSLEEP); 287 if (timo) 288 sleepq_set_timeout(ident, timo); 289 290 /* 291 * Can't call ktrace with any spin locks held so it can lock the 292 * ktrace_mtx lock, and WITNESS_WARN considers it an error to hold 293 * any spin lock. Thus, we have to drop the sleepq spin lock while 294 * we handle those requests. This is safe since we have placed our 295 * thread on the sleep queue already. 296 */ 297 #ifdef KTRACE 298 if (KTRPOINT(td, KTR_CSW)) { 299 sleepq_release(ident); 300 ktrcsw(1, 0); 301 sleepq_lock(ident); 302 } 303 #endif 304 #ifdef WITNESS 305 sleepq_release(ident); 306 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "Sleeping on \"%s\"", 307 wmesg); 308 sleepq_lock(ident); 309 #endif 310 if (timo) 311 rval = sleepq_timedwait(ident); 312 else { 313 sleepq_wait(ident); 314 rval = 0; 315 } 316 #ifdef KTRACE 317 if (KTRPOINT(td, KTR_CSW)) 318 ktrcsw(0, 0); 319 #endif 320 PICKUP_GIANT(); 321 mtx_lock_spin(mtx); 322 WITNESS_RESTORE(&mtx->mtx_object, mtx); 323 return (rval); 324 } 325 326 /* 327 * Make all threads sleeping on the specified identifier runnable. 328 */ 329 void 330 wakeup(ident) 331 register void *ident; 332 { 333 334 sleepq_lock(ident); 335 sleepq_broadcast(ident, SLEEPQ_MSLEEP, -1); 336 } 337 338 /* 339 * Make a thread sleeping on the specified identifier runnable. 340 * May wake more than one thread if a target thread is currently 341 * swapped out. 342 */ 343 void 344 wakeup_one(ident) 345 register void *ident; 346 { 347 348 sleepq_lock(ident); 349 sleepq_signal(ident, SLEEPQ_MSLEEP, -1); 350 } 351 352 /* 353 * The machine independent parts of context switching. 354 */ 355 void 356 mi_switch(int flags, struct thread *newtd) 357 { 358 struct bintime new_switchtime; 359 struct thread *td; 360 struct proc *p; 361 362 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 363 td = curthread; /* XXX */ 364 p = td->td_proc; /* XXX */ 365 KASSERT(!TD_ON_RUNQ(td), ("mi_switch: called by old code")); 366 #ifdef INVARIANTS 367 if (!TD_ON_LOCK(td) && !TD_IS_RUNNING(td)) 368 mtx_assert(&Giant, MA_NOTOWNED); 369 #endif 370 KASSERT(td->td_critnest == 1 || (td->td_critnest == 2 && 371 (td->td_owepreempt) && (flags & SW_INVOL) != 0 && 372 newtd == NULL) || panicstr, 373 ("mi_switch: switch in a critical section")); 374 KASSERT((flags & (SW_INVOL | SW_VOL)) != 0, 375 ("mi_switch: switch must be voluntary or involuntary")); 376 KASSERT(newtd != curthread, ("mi_switch: preempting back to ourself")); 377 378 if (flags & SW_VOL) 379 p->p_stats->p_ru.ru_nvcsw++; 380 else 381 p->p_stats->p_ru.ru_nivcsw++; 382 383 /* 384 * Compute the amount of time during which the current 385 * process was running, and add that to its total so far. 386 */ 387 binuptime(&new_switchtime); 388 bintime_add(&p->p_rux.rux_runtime, &new_switchtime); 389 bintime_sub(&p->p_rux.rux_runtime, PCPU_PTR(switchtime)); 390 391 td->td_generation++; /* bump preempt-detect counter */ 392 393 /* 394 * Don't perform context switches from the debugger. 395 */ 396 if (kdb_active) { 397 mtx_unlock_spin(&sched_lock); 398 kdb_backtrace(); 399 kdb_reenter(); 400 panic("%s: did not reenter debugger", __func__); 401 } 402 403 /* 404 * Check if the process exceeds its cpu resource allocation. If 405 * it reaches the max, arrange to kill the process in ast(). 406 */ 407 if (p->p_cpulimit != RLIM_INFINITY && 408 p->p_rux.rux_runtime.sec >= p->p_cpulimit) { 409 p->p_sflag |= PS_XCPU; 410 td->td_flags |= TDF_ASTPENDING; 411 } 412 413 /* 414 * Finish up stats for outgoing thread. 415 */ 416 cnt.v_swtch++; 417 PCPU_SET(switchtime, new_switchtime); 418 PCPU_SET(switchticks, ticks); 419 CTR4(KTR_PROC, "mi_switch: old thread %p (kse %p, pid %ld, %s)", 420 (void *)td, td->td_sched, (long)p->p_pid, p->p_comm); 421 if ((flags & SW_VOL) && (td->td_proc->p_flag & P_SA)) 422 newtd = thread_switchout(td, flags, newtd); 423 #if (KTR_COMPILE & KTR_SCHED) != 0 424 if (td == PCPU_GET(idlethread)) 425 CTR3(KTR_SCHED, "mi_switch: %p(%s) prio %d idle", 426 td, td->td_proc->p_comm, td->td_priority); 427 else if (newtd != NULL) 428 CTR5(KTR_SCHED, 429 "mi_switch: %p(%s) prio %d preempted by %p(%s)", 430 td, td->td_proc->p_comm, td->td_priority, newtd, 431 newtd->td_proc->p_comm); 432 else 433 CTR6(KTR_SCHED, 434 "mi_switch: %p(%s) prio %d inhibit %d wmesg %s lock %s", 435 td, td->td_proc->p_comm, td->td_priority, 436 td->td_inhibitors, td->td_wmesg, td->td_lockname); 437 #endif 438 sched_switch(td, newtd, flags); 439 CTR3(KTR_SCHED, "mi_switch: running %p(%s) prio %d", 440 td, td->td_proc->p_comm, td->td_priority); 441 442 CTR4(KTR_PROC, "mi_switch: new thread %p (kse %p, pid %ld, %s)", 443 (void *)td, td->td_sched, (long)p->p_pid, p->p_comm); 444 445 /* 446 * If the last thread was exiting, finish cleaning it up. 447 */ 448 if ((td = PCPU_GET(deadthread))) { 449 PCPU_SET(deadthread, NULL); 450 thread_stash(td); 451 } 452 } 453 454 /* 455 * Change process state to be runnable, 456 * placing it on the run queue if it is in memory, 457 * and awakening the swapper if it isn't in memory. 458 */ 459 void 460 setrunnable(struct thread *td) 461 { 462 struct proc *p; 463 464 p = td->td_proc; 465 mtx_assert(&sched_lock, MA_OWNED); 466 switch (p->p_state) { 467 case PRS_ZOMBIE: 468 panic("setrunnable(1)"); 469 default: 470 break; 471 } 472 switch (td->td_state) { 473 case TDS_RUNNING: 474 case TDS_RUNQ: 475 return; 476 case TDS_INHIBITED: 477 /* 478 * If we are only inhibited because we are swapped out 479 * then arange to swap in this process. Otherwise just return. 480 */ 481 if (td->td_inhibitors != TDI_SWAPPED) 482 return; 483 /* XXX: intentional fall-through ? */ 484 case TDS_CAN_RUN: 485 break; 486 default: 487 printf("state is 0x%x", td->td_state); 488 panic("setrunnable(2)"); 489 } 490 if ((p->p_sflag & PS_INMEM) == 0) { 491 if ((p->p_sflag & PS_SWAPPINGIN) == 0) { 492 p->p_sflag |= PS_SWAPINREQ; 493 /* 494 * due to a LOR between sched_lock and 495 * the sleepqueue chain locks, use 496 * lower level scheduling functions. 497 */ 498 kick_proc0(); 499 } 500 } else 501 sched_wakeup(td); 502 } 503 504 /* 505 * Compute a tenex style load average of a quantity on 506 * 1, 5 and 15 minute intervals. 507 * XXXKSE Needs complete rewrite when correct info is available. 508 * Completely Bogus.. only works with 1:1 (but compiles ok now :-) 509 */ 510 static void 511 loadav(void *arg) 512 { 513 int i, nrun; 514 struct loadavg *avg; 515 516 nrun = sched_load(); 517 avg = &averunnable; 518 519 for (i = 0; i < 3; i++) 520 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + 521 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; 522 523 /* 524 * Schedule the next update to occur after 5 seconds, but add a 525 * random variation to avoid synchronisation with processes that 526 * run at regular intervals. 527 */ 528 callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)), 529 loadav, NULL); 530 } 531 532 static void 533 lboltcb(void *arg) 534 { 535 wakeup(&lbolt); 536 callout_reset(&lbolt_callout, hz, lboltcb, NULL); 537 } 538 539 /* ARGSUSED */ 540 static void 541 synch_setup(dummy) 542 void *dummy; 543 { 544 callout_init(&loadav_callout, CALLOUT_MPSAFE); 545 callout_init(&lbolt_callout, CALLOUT_MPSAFE); 546 547 /* Kick off timeout driven events by calling first time. */ 548 loadav(NULL); 549 lboltcb(NULL); 550 } 551 552 /* 553 * General purpose yield system call 554 */ 555 int 556 yield(struct thread *td, struct yield_args *uap) 557 { 558 struct ksegrp *kg; 559 560 kg = td->td_ksegrp; 561 mtx_assert(&Giant, MA_NOTOWNED); 562 mtx_lock_spin(&sched_lock); 563 sched_prio(td, PRI_MAX_TIMESHARE); 564 mi_switch(SW_VOL, NULL); 565 mtx_unlock_spin(&sched_lock); 566 td->td_retval[0] = 0; 567 return (0); 568 } 569